1. Field of the Invention
The present invention relates to a method of manufacturing a motor vehicle door.
2. Description of the Related Art
Conventionally, the following steps are employed in manufacturing a motor vehicle door. Namely, an upper sash and an inner panel are connected to a door panel to thereby assemble a door main body. Then, a pair of front and rear lower sashes are mounted on an inside of the door main body and, subsequently, a window pane (glass) is inserted into the door main body through an opening on an upper end of the door main body in a condition in which the window pane is engaged with the lower sashes. Thereafter, a power transmission mechanism for vertically moving the window pane such as a regulator or the like is mounted on an inside of the door main body through a service opening which is formed in the inner panel, to thereby couple the lower edge of the window pane to the power transmission mechanism.
In this method, however, the work of mounting the power transmission mechanism and the work of connecting the power transmission mechanism and the window pane together have to be carried out without visually confirming the positions thereof. Consequent poor workability is, therefore, a hindrance to the improvement in the productivity. Further, there is still something to be desired in point of quality because the condition in which the window pane and the sashes are engaged is difficult of confirmation.
In Japanese Published Unexamined Patent Application No. 12334/1985, there is also known the following method of manufacturing a motor vehicle door. Namely, an opening is formed in a lower edge of a door main body which is provided with an upper sash. A window pane assembly is made by assembling a window pane and a power transmission mechanism for its vertical movement, into a portal (gate-shaped) guide frame which is located on a base plate at the lower end corresponding to the opening. From a bottom side the window pane assembly is inserted into the door main body through the opening. The upper half of the guide frame is projected upwards through an upper edge opening of the door main body to thereby fit it into the upper sash, and the lower edge opening of the door main body is blocked or closed with the base plate to thereby fix the window pane assembly to the door main body.
In the above-described latter prior art, since the window pane assembly is assembled in advance, the work of mounting the power transmission mechanism and the work of connecting this mechanism to the window pane need not be carried out without visually confirming the actual positions thereof. The workability is therefore improved.
By the way, the upper half of the guide frame has a similar function as the upper sash in point of guiding the window pane. However, since the upper half is projected upwards through the door main body when the window pane assembly is mounted on the door main body, it is likely to be subject to scratches. In order to keep the scratches out of sight, there arises a necessity of providing the upper sash into which the upper half of the guide frame is fitted. In this manner, in the above-described latter prior art, since the upper sash is additionally required aside from the guide frame, there is a disadvantage in that the number of parts increases with a consequent increase in the cost and the weight. Further, since the opening must be formed also in the lower edge of the door main body, there is another disadvantage in that the strength of the door main body decreases.